The well known agricultural practice of forage harvesting consists of cutting either green or mature crop material into discrete particles, and conveying the particles from the field to a storage facility, such as a silo. While in storage the crop material undergoes an acid fermentation to give the particles an agreeable flavor and to prevent spoilage. This overall operation, which is commonly referred to as an ensilage process, converts standing crop in the field to livestock feed, generally called silage.
An essential piece of farm machinery used for producing silage is the forage harvester which is adapted to gather standing or windrowed crop material from the field, chop it into small particles and then convey the cut crop material to a temporary storage receptacle, such as a wagon. Harvesters of this type are either self propelled or pulled by a tractor. Typically, forage harvesters comprise a base unit having a rotary cutter comprising a generally cylindrical configuration with knives peripherally mounted to cooperate with a stationary shear bar for cutting material by a shearing action as it is passed across the surface of the bar. The chopped crop material is then discharged from the harvester through a spout which directs the flow of crop material to a wagon towed behind or along side the harvester.
Forage harvesters, regardless of the type, i.e., both self propelled or pull type, have a crop gathering attachment that initially encounters crop material, as the harvester moves across the field. As mentioned above, the crop being harvested is either standing, such as rows of corn, or lying in the field, such as grass raked into a windrow. In the case of windrowed crop, a pickup attachment, extending from the front of the harvester, typically includes a reel consisting of a plurality of fingers, each of which is moveable through a predetermined path for engaging and picking up the windrowed crop material from the ground. The fingers urge the crop material rearwardly over side-by-side stripper plates, also commonly referred to as tine guards, that define slots through which the fingers extend. The stripper plates terminate in the general vicinity of a transverse auger that consolidates the crop material and feeds it through a rear opening in the header to an access opening in the base unit of the harvester, whereupon it is processed in the manner described above. A typical forage harvester windrow pickup attachment is shown in U.S. Pat. No. 4,495,756, issued on Jan. 29, 1985 in the name of J. G. Greiner, et al, hereby incorporated by reference.
In present day forage harvesters the pickup attachment is supported either by ground support means, the base unit to which it is attached, or a combination of the base unit and ground support means. Ground support techniques may consist of skid assemblies, wheels mounted on outrigger arm assemblies, rollers, or a combination of these approaches. Regardless of the support system employed, it is desirable to support the attachment a sufficient distance above the ground to prevent damage to the reel elements without having a deleterious affect on its ability to pick up the entire windrow.
During forage harvesting operations, varying stubble heights are encountered from day to day, and sometimes field to field, requiring a departure from the recommended minimum height at which the attachment normally operates. To this end, the present invention is directed to an improved windrow pickup attachment for forage harvesters having new and unique features for improving operating height adjustment capabilities.